Fire-fighting foam generator



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" i? ataw w BY fw United States Patent 3,142,340 FIRE-FIGHTING FOAM GENERATQR Will B. Jamison, Greensburg, Pa, assignor to Safety Development Corporation, Greensburg, Pa, a corporation of Ohio Filed June 29, 1962, Ser. No. 206,219 11 Claims. (Cl. 169-15) This invention relates to a fire-fighting foam generator of the type adapted to produce a high expansion foam plug, and more particularly to a foam generator of the type described which is particularly suited for use as a permanent installation in a building or the like, the generator being turned on automatically upon the oc currence of a fire in the building.

In copending application Serial No. 13,103 filed March 7, 1960, a fire-fighting foam generator is described which comprises a wind tunnel having a foam-forming net stretched across one end and a fan or the like at the other end which forces air axially through the tunnel. Between the fan and the net are one or more nozzles which spray a solution containing a wetting or foaming agent onto the net. The net is preferably loosely knit from an absorbent material such as cotton or nylon, the arrangement being such that a plurality of apertures are formed in the material across which bubbles may form. When the solution containing a wetting agent is sprayed onto the net by the nozzles, it will be absorbed by the net until such time as the net becomes saturated. At this point, the solution bridges across the various apertures in the net; while the air currents forced through the tunnel by the fan cause the formation of bubbles at these apertures. The mass of bubbles or foam plug formed by the net has an expansion ratio of at least 30 to 1 and up to 2000 to 1, meaning that 2000 volumes of foam can be generated for one volume of solution sprayed onto the net.

In contrast to low expansion foams, a high expansion foam plug formed in this manner has the ability of filling the entire volume of a building or other enclosure. Furthermore, the foam plug can effectively travel around corners and from room to room Within the building so that the foam-generating equipment need not be positioned along a straight-line path with respect to the fire zone as would be the case, for example, with a water jet from a fire hose.

In the operation of the device, the foam plug fills the entire volume of the building and travels toward the fire zone where the foam forms steam which eventually smothers the fire, and this regardless of whether the fire is due to burning oil, chemicals or other substances where a fire hose usually cannot be employed. In addition to its other advantages, the foam plug is such that the problem of water damage encountered with a fire hose or an automatic sprinkler system is entirely eliminated, since, although the foam fills the entire area of the building surrounding the fire, its water content is relatively small and does not soak furniture and other fixtures within the building. Furthermore, the foam has the ability to travel under as well as over objects. Thus, in the case of a fire occurring beneath an aircraft within a hanger, the foam plug will travel under as well as over the aircraft to extinguish the blaze, a feat which is impossible with other types of fire-fighting equipment.

As was mentioned above, the present invention is primarily intended for use in permanently-installed fire control systems for guildings, the foam generator being turned on automatically whenever the heat from a fire triggers an automatic fire detecting device. In this respect, the system is somewhat similar in application to an automatic sprinkler system; however, it does not require an extensive network of pipes throughout the building and ice instead of spraying the area with water when the fire occurs, the aforesaid nozzles of the foam generator spray the net while the fan is simultaneously turned on to form a foam plug which fills the entire area of one or more rooms of the building until the fire is extinguished.

Since the foam-forming net of the generator is fabricated from nylon, cotton or some other similar material, the heat from a flash-fire or the like could very well damage the dry net before the automatic fire detecting device turns on the nozzles to wet it. Accordingly, it becomes necessary to provide some means for protecting the net of the generator in the event of a flash-fire until the aforesaid nozzles are turned on to wet the net.

As an overall object, the present invention seeks to provide apparatus for protecting the net of a fire-fighting foam generator against heat prior to its being wetted with a foam-generating solution.

More specifically, an object of the invention is to provide fire-resistant closure means for the aforesaid net of a permanently-installed foam generator, the closure means being automatically removed or opened when a fire occurs and the net becomes wetted.

In accordance with the invention, there is provided a wind tunnel having a fan or the like at one end for forcing air axially through the tunnel, a foam-forming net at the other end of the tunnel, nozzle means between the fan and the net for spraying a solution containing a foaming agent onto the net, closure means for the net at the forward end of the wind tunnel for protecting the net from heat before it is sprayed with the foaming agent solution, and means responsive to the passage of liquid through said nozzle means for opening the closure means to permit a foam plug to be discharged from the forward end of the generator. Preferably, the closure means comprises normally closed louvers or doors, and the means for opening the louvers or doors comprises cylinder and piston means actuable in response to the back pressure created in the conduit leading to the aforesaid nozzle means when such nozzles initially spray the net with a foam-forming solution. In this manner, it can be seen that the net will be wetted before the louvers or doors are opened with the result that the net will be protected from flash-fires. In the usual case, an automatic fire detecting device will initially supply a foam-forming solution to the nozzles, and the back pressure from these nozzles, mentioned above, will open the louvers or doors.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIGURE 1 is a partially broken-away side view of a fire-fighting foam generator incorporating one embodiment of the present invention wherein louvers are employed to normally cover the net of the foam generator prior to its being wetted;

FIG. 2 is an end view of the generator of FIG. 1 as viewed from the right substantially along line IIII of FIG. 1 and showing the intake portion of the generator;

FIG. 3 is an end view of the generator of FIG. 1 as viewed from the left substantially along line III-III of FIG. 1 and showing the louver arrangement of the invention;

FIG. 4 is a detailed end view of the louver actuating mechanism for the embodiment of the invention shown in FIGS. 1, 2 and 3;

FIG. 5 is a detailed side view of the mechanism of FIG. 4; and

FIG. 6 is a plan or elevational view of another embodiment of the invention wherein hinged doors, rather than louvers, are employed to cover the net of the foam generator prior to its being wetted.

Referring now to the drawings, and particularly to FIGS. 1, 2 and 3, a fire-fighting foam generator, generally indicated by the reference numeral 10, is mounted within an opening 12 of a building wall 14. Supports, not shown, may be provided between the wall 14 and the opposite ends of the generator 10 to give it additional structural rigidity.

The generator 10 itself comprises a wind tunnel formed from five sections, each of which is fabricated from angle irons or the like and sheet metal. The first section 16 comprises a weather hood which houses a fan 18, the fan being driven through belt 20 by means of an electric motor 22. The shaft 24 for fan 18 is supported in bear ings 26, these bearings, in turn, being carried on a support structure 28 which extends outwardly from a plate 30 (FIG. 2) supported at its edges on angle irons 32 (FIG. 1) extending around the periphery of the wind tunnel forming the foam generator 10. As best shown in FIG. 2, the plate 30 has a circular opening 34 provided therein which has a diameter substantially equal to the diameter of the fan 18. A screen 37 covers the inlet end of the hood 16 for the purpose of preventing solid objects from being sucked into the wind tunnel.

Connected to the forward end of the weather hood 16 is a section 36 having an access door 39 therein; while ahead of the section 36 is another section 38 in which are positioned nozzles 40, all of these nozzles being connected to a common conduit 42. Ahead of section 33 is a short section 44 which, in the embodiment of the invention shown herein, has a plurality of staggered rods or bars 46 extending between its sides. Stretched around the various support rods 46 in a zig-zag or corrugated configuration is a foam-forming net 48 which preferably comprises a cloth material of nylon or cotton loosely knit to provide a plurality of apertures therein.

For a full and detailed description of the manner in which a foam plug is formed at the net 48, reference may be had to the aforesaid copending application Serial No. 13,103. For purposes of the present application, however, it will be sufficient to state that when a solution containing a foaming or wetting agent is sprayed onto the not by nozzles 40 and the motor 22 turned on so as to rotate the fan 18, foam is produced at the left side of the net as viewed in FIG. 1 by the air from fan 18 blowing bubbles from films of liquid stretched over the aforesaid holes or apertures in the net 48. The resulting foam plug can have an expansion ratio of as high as 2000 to 1 and will fill the entire volume of a building or other enclosure. As the foam is generated, it will issue from the forward end of the generator as billowy, light bubbles which travel forward and eventually fill the entire building. When this mass of bubbles or foam plug reaches the fire zone, the heat of the fire forms steam from the bubbles, which steam eventually smothers the fire in a very elficient manner.

As was mentioned above, the present invention is particularly adapted for use with fire-fighting foam generators of this type intended for use as permanent building installations. In such installations it is necessary to protect the net 48 from the heat of flash-fires and the like; and for this purpose an end section 50 is connected to the forward end of section 44 which carries the net 48. As shown, the section 50 carries three rotatable louvers 52, 54 and 56 each of which is mounted for pivotal movement on the vertical sides of the section 50. The louvers 52-56 are shown closed in FIGS. 1 and 3; however they may be opened by rotating them about their pivotal connections to the sides of section 50 as indicated by the arrow 58 in FIG. 1.

In order to rotate the louvers 52-56 in the direction of arrow 58 and thus open them to permit foam to be delivered from the forward end of generator 10, the actuating mechanism of FIGS. 4 and may be employed. Each louver 52, 54 and 56 is mounted at one end of a pivot bar or axle 60, 62 or 64, respectively. The bars 60-64 are, in turn, connected to linkages 66, 68 and 70, respectively (FIG. 5). The linkages 66-70 are each pivotally connected to a bifurcated bar 72, the upper end of the bar 72 being connected to a clevis 74. This clevis is connected through linkage 76 to the piston rod of a pneumatic cylinder and piston arrangement, generally indicated at 78.

Referring again to FIG. 1, the generator 10 includes fire sensing apparatus 80 which, in response to the heat of a fire within a building, will trigger a motor control circuit 82 to start the motor 22 and fan 18. At the same time, the fire sensing apparatus 80 actuates a motor 82 to open a valve 84 in the conduit 42. The inlet port of valve 34 is connected as shown to a source of water under pressure 86, which source of water may be the conventional tap water available in any building. After passing through valve 84, the water from source 86 passes through an in-line proportioner or venturi arrangement 88 where it is mixed with a foaming agent from source 90. From the in-line proportioner 88 the mixture of water and foaming agent passes to the nozzles 40 and thence through the nozzles where it is sprayed onto the net 48 to form a foam plug in the manner described above. Connected to the conduit 42 is a pilot line 92 which is connected to the upper variable volume chamber of the pneumatic cylinder 7 8. When the generator is not in use, the conduit 42 and pilot line 92 will be dry (i.e., empty).

When a fire is sensed by apparatus 80, the following things happen: First, the motor control circuit 82 starts the motor 22 to rotate the fan 18. At the same time, it actuates the motor 82 to open valve 84, and when valve 84 opens liquid is forced through the in-line proportioner 88 with the resulting mixture of water and foaming agent being forced through the restricted orifices of nozzles 40. When the solution of water and foaming agent passes through the nozzles 40, a back pressure is created in the conduit 42 which creates a pressure head in the pilot line 92, this pressure head acting to pressurize the aforesaid variable volume chamber of the pneumatic cylinder 78 to push the clevis 74 and bar 72 downwardly, thereby rotating the louvers 52, 54 and 56 in the direction of arrow 58 to open the end of the generator 10 and permit the foam plug to pass therethrough. It will be appreciated, however, that until the foaming agent so lution is forced through the restricted orifices of the nozzles 40, the pressure within conduit 42 will not be great enough to actuate the cylinder 78. Consequently, by the time that the cylinder 78 is actuated to open the louvers 52-56, the net 48 will already have been wetted. In the event that extreme heat or flames are directly in front of the generator 10, such heat cannot damage the net 48 since when the louvers 52-56 are closed, they will protect the net; and after they are opened, the net will have already been wetted, which will prevent damage thereto by the heat.

Another embodiment of the invention is shown in FIG. 6 which operates on the same principle as the embodiment of FIGS. 1-5, except that in this case the louvers 52-56 are replaced by doors 94 and 96 which are hingedly connected to the sides of the forward section 50 by means of hinges 98. As shown, the doors 94 and 96 overlap as at 100 and are normally held in closed position by means of latch bars 102 and 104 extending through the top and bottom, respectively, of the forward section 50. These latch bars may be removed by pneumatic cylinders 106 and 108, respectively, having their lower variable volume chambers connected to conduit 92, the arrangement being such that when the foaming agent solution passes through the nozzles 40 and wets the net 48, pressure will build up in the pilot line 92 to move the latch bars 102 and 104 upwardly and downwardly, respectively, thereby permitting the doors 94 and 96 to open. In most cases, the force of the air from fan 18 will be sufiicient to open the doors 94 and 96 after the latch bars 102 and 104 are removed. If desired, however, the hinges 98 may be spring-loaded such that the doors 94 and 96 will automatically spring open regardless of the force of the air from fan 18.

The doors 94 and 96 will be opened only in the event of a fire; and these doors may be manually closed and the latch bars 102 and 104 placed in position. If desired, however, automatic means may be provided for this purpose. Similarly, the louvers 52-56 shown in FIGS. 1 and 3 may be spring-loaded whereby they will automatically snap back into closed position after a fire is extinguished and the pressure within conduit 42 drops. In most cases, however, the occurrence of a fire will be infrequent enough such that the louvers can be returned to their closed positions manually without any great inconvenience.

The foregoing description of the invention has been limited to an embodiment of the invention wherein the foam generator extends through an opening in a building wall. It should be understood, however, that when it is not necessary to have the gas within the bubbles of the foam plug of pure air (to permit people to breathe in the foam safely), it may be more convenient and desirable to install the foam generator entirely within the building rather than have it extend through a building wall as shown in FIG. 1. In this way, it becomes unnecessary to provide an escape means for the air already in the building. Thus, the fan will always operate against a constant pressure, as it might not if doors or windows are open to provide an escape means for the displaced air. This arrangement (i.e., the foam generator entirely within the building) is particularly adaptable for use in the field of decontamination. For example, in an area having radioactive particles dispersed in the atmosphere, it is possible to generate outof the fixed volume of atmosphere a large mass of bubbles. In this case, the foamgenerating equipment can be located within the fixed volume of an enclosure andproceeds to capture all of the contaminated atmosphere within bubble formations. For a period of time, as for example, twenty-five minutes or so, all of the atmosphere is maintained in aspirated condition with foam. The foam generator is kept operating to generate foam at the same rate it is broken down. The radioactive particles, some of which are very small, on the order of micron and sub-micron size, will impinge the inner surface of the foam and being wetted, will be carried down with the drainage of the foam as it fractures into the liquid phase and releases the inner air. During the twenty-five minute period or so, all of the radioactive particles will become wetted and will be carried down with the foam until it reaches the floor where it is washed away. From actual tests experience, virtually all airborne radioactive material can be removed from an enclosure in the manner described.

In the case where the foam generator is located entirely within a building or other enclosure, the doors or shutters protect the net on the discharge side of the generator as described above. Such protection, however, is not required on the inlet side of the generator since the distance between the air inlet and the net is relatively great, and the obstructions at this side (fan blades, piping and protective screen) give good protection.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net at the other end of the tunnel, nozzle means between said air-moving means and said net for spraying a solution containing a foaming agent onto the net, closure means for the net at said other end of the tunnel for protecting said net from heat before it is sprayed with said solution, conduit means for supplying said solution to the nozzle means, and means operable when pressure builds up in the conduit means as liquid passes through said nozzle means for opening said closure means to permit the foam plug formed at said net to be discharged from said other end of the wind tunnel.

2. Apparatus for generating a fire-fighting foam plug comprising a stationary wind tunnel positioned at least partially within a building structure and having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net at the other end of the tunnel, nozzle means between said air-moving means and said net for spraying a solution containing a foaming agent onto the net, closure means for the net at said other end of the tunnel for protecting said net from heat before it is sprayed with said solution, conduit means including a normally closed valve device for supplying said solution to the nozzle means when the valve device is open, means responsive to the occurrence of a fire within said building for opening said valve device, and means operable after the valve device is opened for opening said closure means to permit a foam plug at said net to be discharged from said other end of the wind tunnel.

3. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel extending through a building wall and having air-moving means at one end of the tunnel on the outside of said building for forcing air axially through the tunnel, a foam-forming net at the other end of the tunnel inside said' building, nozzle means between said air-moving means and said net for spraying a solution containing a foaming agent onto the net, closure means for the net at said other end of the tunnel for protecting said net from heat within the building before it is sprayed with said solution, conduit means for supplying said solution to the nozzle means, and means operable when pressure builds up in the conduit means as liquid passes through said nozzle means for opening said closure means to permit a foam plug formed at the net to be discharged from said other end of the wind tunnel and into the interior of said building.

4. The apparatus of claim 3 and including means for detecting the occurrence of a fire within said building, and means operable when the fire detecting means detects a fire in the building for supplying a solution containing a foaming agent to said conduit.

5. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net extending across the tunnel in close proximity to the other end thereof, nozzle means between the net and said air-moving means for spraying a solution containing a foaming agent onto the net, normally closed louver means at said other end of the tunnel for covering said net and adapted to protect said net from heat until it becomes wetted by a spray from the nozzle means, and means for opening said louver means to permit a foam plug to be delivered from said other end.

6. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net extending across the tunnel in close proximity to the other end thereof, nozzle means between the net and said air-moving means for spraying a solution containing a foaming agent onto the net, normally closed louver means at said other end of the tunnel for covering said net and adapted to protect the net from heat until it becomes wetted by a spray from the nozzle means, cylinder and piston means for opening said louver means, said cylinder and piston means defining at least one variable volume chamber which, when pressurized, will cause the louver means to open, first conduit means for conducting a solution containing a foaming agent to said nozzle means, and second conduit means connected between said first conduit means and said variable volume chamber whereby the variable volume chamber will be pressurized to open the louver means when a solution containing a foaming agent is conducted through the first conduit means to said nozzle means and the nozzle means creates a back pressure in the first conduit means upon the delivery of a spray therefrom.

7. The apparatus of claim 6 wherein said cylinder and piston means is of the pneumatic type, the variable volume chamber thereof being pressurized by air which is compressed in the second conduit means by a liquid pressure head created in the first conduit means upon delivery of liquid from said nozzle means.

8. The apparatus of claim 6 and including means for detecting the occurrence of a fire, and means responsive to said detecting means for conducting a solution containing a foaming agent under pressure through said first conduit means to the nozzle means.

9. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net extending across the tunnel in close proximity to the other end thereof, nozzle means between the net and said air-moving means for spraying a solution containing a foaming agent onto the net, door means hinged to the periphery of said tunnel at said other end and adapted to cover said net when closed and to expose the net when open to permit a foam plug to be delivered from said other end of the generator, latch means for normally holding the door means closed, conduit means for supplying said solution to the nozzle means, and means operable when pressure builds up in the conduit means as liquid passes through said nozzle means for actuating the latch means to permit the door means to open.

10. Apparatus for generating a fire-fighting foam plug comprising a wind tunnel having air-moving means at one end thereof for forcing air axially through the tunnel, a foam-forming net extending across the tunnel in close proximity to the other end thereof, nozzle means between the net and said air-moving means for spraying a solution containing a foaming agent onto the net, door means hinged to the inner periphery of said tunnel at said other end and adapted to cover said net when closed and to expose the net when open to permit a foam plug to be delivered from said other end of the generator, latch means for normally holding the door means closed, conduit means for conducting a liquid containing a foaming agent to said nozzle means, means for sensing the occurrence of a fire, means actuated when a fire is sensed by said last-named means for forcing a solution containing a foaming agent through said conduit means to the nozzle means, and means responsive to a back pressure created in said conduit means in response to the issuance of liquid from said nozzle means for actuating the latch means to permit the door means to open.

11. Apparatus for generating a fire-fighting foam plug comprising a Wind tunnel extending through a building wall and having air-moving means at one end of the tunnel outside of the building for forcing air axially through the tunnel, a foam-forming net extending across the tunnel in close proximity to the other end thereof which is inside the building, nozzle means between the net and said air-moving means for spraying a solution containing a foaming agent onto the net, door means hinged to the inner periphery of said tunnel at said other end and adapted to cover said net when closed and to expose the net when opened to permit a foam plug to be delivered from said other end of the generator, latch means for normally holding the door means closed, conduit means including a normally closed valve device for supplying said solution to the nozzle means when the valve device is opened, means for sensing the occurrence of a fire within said building and for opening said valve device, and means operable when pressure builds up in said conduit means after the valve device is opened for actuating the latch means to permit the door means to open.

References Cited in the file of this patent UNITED STATES PATENTS 1,568,281 Jones Jan. 5, 1926 1,873,161 Taucher Aug. 23, 1932 3,055,285 Gaylord Sept. 25, 1962 3,065,797 Barnes Nov. 27, 1962 OTHER REFERENCES Firefighting in Underground Roadways, Eisner and Smith, published by British Ministry of Fuel and Power, June 1956. 

1. APPARATUS FOR GENERATING A FIRE-FIGNTING FOAM PLUG COMPRISING A WIND TUNNEL HAVING AIR-MOVING MEANS AT ONE END THEREOF FOR FORCING AIR AXIALLY THROUGH THE TUNNEL, A FOAM-FORMING NET AT THE OTHER END OF THE TUNNEL, NOZZLE MEANS BETWEEN SAID AIR-MOVING MEANS AND SAID NET FOR SPRAYING A SOLUTION CONTAINING A FORAMING AGENT ONTO THE NET, CLOSURE MEANS FOR THE NET AT SAID OTHER END OF THE TUNNEL FOR PROTECTING SAID NET FROM HEAT BEFORE IT IS SPRAYED WITH SAID SOLUTION, CONDUIT MEANS FOR SUPPLYING SAID SOLUTION TO THE NOZZLE MEANS, AND MEANS OPERABLE WHEN PRESSURE BUILDS UP IN THE CONDUIT MEANS AS LIQUID PASSES THROUGH SAID NOZZLE MEANS FOR OPENING SAID CLOSURE MEANS TO PERMIT THE FOAM PLUG FORMED AT SAID NET TO BE DISCHARGED FROM SAID OTHER END OF THE WIND TUNNEL. 